MOTIONS OF INSECTS. 



287 



Another peculiarity also distinguishes them. Base covers 

 (tegulce), or small concavo-convex shields, protect the base 

 of the wings from injury 1 or displacement. 



The most powerful fliers in this order are the humble-bees, 

 which, like the dung-chafers (Geotrupes), traverse the air in 

 segments of a circle, the arc of which is alternately to right 

 and left. The rapidity of their flight is so great that, could 

 it be calculated, it would be found, the size of the creature 

 considered, far to exceed that of any bird, as has been proved 

 by the observations of a traveller in a railway carriage 

 proceeding at the rate of twenty miles an hour, which was 

 accompanied, though the wind was against them, for a con- 

 siderable distance by a humble-bee (Bombus subinterruptus 

 K.), not merely with the same rapidity, but even greater, as 

 it not unfrequently flew to and fro about the carriage or 

 described zigzag lines in its flight.' 2 The aerial movements 

 of the hive-bee are more direct and leisurely. When leaving 

 the hive for an excursion, I have observed that as soon as 

 they come out they turn about as if to survey the entrance, 

 and then, wheeling round in a circle, fly off. When they return 

 to the hive, they often fly from side to side, as if to examine 

 before they alight. When swarming, the heads of all are turned 

 towards the group at the mouth of their dwelling ; and upon 

 rising into the air these little creatures fly so thick in every 

 direction, as to appear like a kind of net-work with meshes of 

 every angle. The queen also, upon going forth, when her ob- 

 ject is to pair, after returning to reconnoitre, begins her flight 

 by describing circles of considerable diameter, thus rising 

 spirally with a rapid motion. 3 The object of these gyrations 

 is probably to increase her chance of meeting with a drone. 

 I have not much to tell you with respect to the flight of 

 other insects of this order, except that a spider-wasp (Pompilus 

 viaticus), whose sting is redoubtable, and which often, when 

 we are in the vicinity of sandy sunny banks, accompanies our 

 steps, has a kind of jumping movement when it flies. 



The next order, the Diptera, consists altogether of two- 



1 Kirby, Mon. Ap. Angl. i. 96. 107. t. v. f. 8. dd. 



2 Philos. Mag., quoted in Burmeister's Manual of Ent. 464. 



3 Huber, i. 38. 



